Argument Stack Functions

When describing the GridRPC call functions, we mentioned that there is an alternate calling
style that uses an argument stack. With the following functions it is possible to construct the
arguments to a function call at run-time. When interpreted as a list of arguments, the stack is
ordered from bottom up. That is, to emulate a function call f(a,b,c), the user would push the
arguments in the same order: push(a); push(b); push(c);.

newArgStack creates a new argument stack.

pushArg pushes the specified argument onto the stack.

popArg removes the top element from the stack.

destructArgStack frees the memory associated with the specified argument stack.